A data segment is encrypted to produce an encrypted data segment, and a data tag associated with the data segment is generated. The encrypted data segment is encoded to generate a set of encoded data slices. At least a read-threshold number of encoded data slices are required to reconstruct the encrypted data segment. A set of write slice requests, which includes the set of encoded data slices and the data tag, is transmitted to a DSN memory. A determination is made, based on the data tag, whether a first encoded data slice of the set of encoded data slices is a duplicate of a second encoded data slice already stored within the DSN memory. If it is a duplicate, rather of storing the first encoded data slice, a reference to a location of the second encoded data slice is stored.